doc: announce ABI change for security session
doc: announce ABI change for security session

Add 'uint64_t opaque_data' inside struct rte_security_session.
That allows upper layer to easily associate some user defined
data with the session.
Proposed new layout for:
struct rte_security_session {
	void *sess_private_data;
	/**< Private session material */
+	uint64_t opaque_data;
+	/**< Opaque user defined data */
};

Signed-off-by: Konstantin Ananyev <cbd5212b59ab42a210d72992d23a3aa17cfd3eaf@intel.com>
Acked-by: Mohammad Abdul Awal <38374f06acadb758f6fbf72e9fd35fff1cac6ad2@intel.com>
Acked-by: Fan Zhang <b46d470dc79aa6fd718cd24d07380f6203b7fc3c@intel.com>
Acked-by: Akhil Goyal <74d7c4c993a22c1d4f60c46ff3d95c969a24a25c@nxp.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk